In recent years, code readers capable of tracing articles in distribution channels from a manufacturing stage to a consumption stage or a disposal stage, so called traceability, have been considered important, and such code readers for the purpose of the traceability have become popular. Further, other than the traceability, the code readers have been used in various fields.
In general, the code readers have a configuration to read images of bar codes or two-dimensional codes, etc., which are attached to workpieces, and the codes on the obtained images are read and binarized by image processing, and they are decoded so as to read information. The code readers are the devices which optically read information, so that it is also called as optical information reading devices (see e.g. Japanese Patent Application Publication No. 2016-33787 and Japanese Patent Application Publication No. H09-6891).
In Japanese Patent Application Publication No. 2016-33787, it is configured to perform a tuning step in which imaging parameters such as an exposure time, a gain of a camera, etc. are automatically set to be an optimum value, before operation of an optical information reading device, that is, at the time of setting.
Further, in Japanese Patent Application Publication No. H09-6891, a correspondence table between a conveyance speed of a workpiece and an appropriate exposure time is prepared in advance, and it is configured that the exposure time in response to the conveyance speed can be set by using the correspondence table.